252 Bailey 07i the Siliceous Spicules 



Art. XXI. — on THE EXISTENCE OF SILICEOUS? SPICULiE 

 IN THE EXTERIOR RAYS OF ACTINIA; AND MEMORANDA 

 CONCERNING THE SILICEOUS ANIMALCULES OF BOS- 

 TON. By G. W. Bailey, Prof. Chem. Min. and Geol., U. S. Military 

 Academy. (Communicated June, 1842.) 



During a recent visit to Boston, in April, I eagerly em- 

 braced the long wished for opportunity to examine the marine 

 siliceous infusoria of our coast ; for I hoped to be able to de- 

 tect, in a living state, some of those elegant forms which 

 occur so abundantly in the fossil infusorial strata of the marine ^^ 

 tertiary of Virginia. I was aware that Ehrenberg had de- 

 tected many of these forms in a living state, in the sea at 

 Cuxhaven and elsewhere, and I felt confident that our shores 

 must abound in similar forms. In company with Dr. Gould, 

 I visited the docks near the Chelsea ferry, and collected from 

 the immersed logs, &c., a quantity of filamentous Algae, 

 among which I knew that many of the objects of my search 

 were likely to be entangled. On subjecting them to a mi- 

 croscopic observation I detected a number of very interesting 

 and beautiful forms, although the season was not the most 

 favorable. The first objects which attracted my attention 

 were great numbers of siliceous spiculae, precisely similar to 

 those found fossil in the infusorial stata above referred to j 

 these I found among the Algoe, and also more abundantly in 

 the mud of the docks. These spiculae resemble those found 

 in some species of Spongia and Tethya. and I believe that 

 Ehrenberg refers the fossil ones to these genera ; but an ob- 

 servation which I made leads me to suspect that some of 

 them, at least, are derived from the exterior rays of Actinia. 

 On examining, with a high magnifying power, the rays of a 

 large species of Actinia which had an orange colored base and 

 olive rays (A. marginata, Lesueur?) I found that the white 

 rays, which form the exterior circle, appeared to differ from all 

 others, being filled with spiculae, arranged with great regular- 

 ity, and in countless numbers, radiating from the axis of each 

 arm, (See fig. 1, b and c.) Each of the spiculae was perfor- 

 ated with a longitudinal cavity, from which was protruded a 



